Contact member for oil-immersed circuit interrupters



Nov. 17, 1931.

s. T. SCHOFIELD 1,831,844

CONTACT'MEMBER FOR OIL IMMERSED CIRCUIT INTERRUPTERS WITNESSES:

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Filed Sept. '7. 1926 2 Sheets-Sheet 1 Fly. L

ATTO'RNEY Nov. 17, 1931. s. T. SCHOFIELD 1,831,844

CONTACT MEMBER FOR OIL IMMERSED CIRCUIT INTERRUPTERS Filed Sept. 7, 1926 2 Sheets-Sheet 2 ga; 7 II I I Iv l: I: '1 9 a /2 a A /2 /3 k", 6 /J /3 l8 /7 7 WITNESSES INVENTOR fin- $2M Jim/6 0 TJcho/ie/d.

g ATTORNEY Patented Nov. 17, 1931 STANLEY '1'. SCHOFIEIJD, OF WILKIN SBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & VANIA MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- OONTACT MEMBER FOR OIL-IMME-R-SED CIRCUIT INTERRUPTERS Application filed September 7, 1926. Serial No. 133,797.

My invention relates to electrical switching apparatus and more particularly to areing contact members for oil-immersed circuit interrupters. 7

One object of my invention is to provide a contact member that shall have a rounded contour for producing a partial rolling movement during its engagement with a co-operating contact member.

Another object of my invention is to provide an arcing contact finger that shall produce a partial rolling movement across the face of a second contact member upon its engagement with, and withdrawal from, the second contact member.

Another object of my invention is to provide a contact finger for circuit interrupters that shall partially roll to an advanced position during the withdrawalof a co-operating contact member and thatfshall snap into its circuit-closing positionafter the withdrawal ofthe co-operating contact member.

A further object of my invention is to provide an arcing contact member for circuit interrupters that shall be characterized by having a partial rolling movement and a partial sliding movement across the face of a cooperating contact member.

In contact fingers, as heretofore constructed, it has been customary to provide the con tact member with a smooth face that slides into and from its final position against a cooperating contact member. During such sliding movement, arcs are drawn between the contact members that tend. to pit their flat faces. When such contact member has become thickly pitted, the depressions and projections resulting therefrom interfere with the sliding movement of the co-operating contact member, with a corresponding lessening of the current-conducting capacity of the contact fingers and a marked increased in their rise in temperature.

By providing a contact member that engages its' co-operating contact member with a partial rollingmovement, the frictionexisting between the co-operating contact'mem hers is reduced by reason'of the curve surface on the arcing'finger that is able to 'roll over the inequalities in the surfaces of the co-operating contact member, guished from sliding thereover.

Inthe accompanying drawings,

. Fig. 1 is a view, in elevation, of a portion of acircuit interrupter embodying my invention,

Fig. 2 is a view, partially in elevation and partially in section, of the arcing contact members that are employed in connection with the circuit interrupter mechanism shown in Fig. 1, at an intermediate position during their circuit closing movement,

Fig. 3 is an edgeview of one of the contact members shown in Fig. 2,

Fig. 4 is an elevational view of the contact members shown in Fig. 2 in their circuit-closing position, and,

Fig. 5 is a View of the contact members at an intermediate position during their circuit-opening movement.

My invention comprises, in general, a circuit interrupter 1 having a pair of main stationary contact members 2 and a co-operating bridging member 3 that is actuated by a suitable pull rod 4, together with stationary arcing contact members or fingers 5 that are supported by the main contact members2 for co-operation withmovable contact members,

such as switch blades 6, thatare carried by the-bridging member 3. i v i The elements l to 4', inclusive, may be of any preferred type, since the details of their construction form no part of the present invention, except insofar as they are necessary to complete the combinations with the arcing contact members 5. and 6, hereinafter more fully described. 1

A pair of arcing contact members 5 are secured, by means of a bolt 7, to each of the stationary contact members2, which constitute base portions for the members 5. Each as distinof the contact members or fingers 5 comprises a supporting strap'8, a tensioning spring 9, a current-conducting'shunt 11 and a contact member 12 that is pivotally supported, as at 13, at the end of the'supporting strap 8. The straps 8 are loosely mounted on the bolts 7, the upper ends of the straps extending through slots in the base portion of greater thickness" than the strap, to permit a limited amount of play therebetween, for a purpose to be hereinafter described.

Referring particularly to Fig. 2, each contact member 12 comprises an inverted cylindrical portion 14 that extends upwardly and encloses the lower ends of the strap 8 and spring 9. The spring 9 bears upon a projecting lug 15 mounted within the cylindrical portion 14 by means of rivets 16, so that the lug 15 is free to turn relatively to the spring 9. Exteriorly of the cylinder 14 is mounted a contacting block 17, of peculiar configuration, for co-operation with the moving contact member 6. The upper, or inner, portions of the contacting blocks 17 are provided with fiat seats 18 for the reception of the contact members 6. \Vhen the switch blade 6 is confined in a pair of the seats 18, they serve as a latch for delaying the separating movement of the blade 6 until a suificient'pressure is supplied thereto to spread the contact fingers 5 apart.

Below, or outwardly from, the seats 18 the contacting blocks 17 have rounded contours, as at 19, for securing a partial rolling movement of the contacting blocks 17 across the faces of the contact member 6 when the two contact members are moved into and out of engagement with each other.

WVhen it is desired to close the arcing contact members, the contact member 6, which is usually in the form of a switch blade, is moved upwardly and into engagement with the outer curved edges 19 of the contacting blocks 17. Further upward movement of the contact member 6 causes the contact members 12 to turn about their pivotal supports 13 away from the contact member 6 and against the force of the springs'9. The deflection of the contact members 12 is entirely compensated for by the springs 9, and no relative movement takes. place between the supporting straps 8 and the bolts 7. Accordingly, the contacting block-s17 partially roll and partially slide across the faces of the contact members 6 until the latter pass the curved portions 19 and enter the seats 18, which is the final circuit closing position of the arcing contact members, as is shown in 4. When the contact member 6 is in its final circuit-closing position between a pair of contact fingers 5, the springs 9 bias the contact fingers 5 into firm engagement with the moving contact member 6.

' Referring to Fig. 5, when the contact memher 6 is withdrawn from engagement with the contact members 12, they tend to turn about their pivots 13 inwardly or towards the moving contact member 6. However, their amount of movement in this direction is limited by the engagement of the upper walls of the cylinder 14 with their support ing straps 8 and, accordingly, since the application of the turning force is above the cen ter line of the pivots 13, the supportingstraps 8 are both forced outwardly relative to the moving contact member 6. This pressure causes them to shift their positions relative to the bolts 7 from that shown in Figs. 2 and 1' to that shown in Fig. 5. Accordingly, the contacting blocks 17 partially roll and partially slide across the faces of the moving contact member 6 as it leaves the contact fingers 5.

\Vhen the contact member 6 has cleared the ing and a partial sliding movement across the faces of a co-operating contact member, while that co-operating member is moving into and out of engagement with a seat formed in the first-mentioned contact member.

It is to be understood that such changes in the proportioning, shapingand disposition of the component parts of my invention may be made as shall fall within the scope of the appended claims.

I claim as my invention:

1. A contact member including support means, a strap loosely supported thereon, a contact finger pivotally supported on said strap and having a contact-making face the outer contour of which is a curve comprising two sectors offset relative'to each other.

2. A contact member including support means, a strap loosely supported thereon, a contact finger pivotally supported on said strap and having a contact-making face the contour of which is a discontinuous curve.

3. A contact member including support means, a strap loosely supported thereon, a contact finger pivotally supported on said strap and having a contact-making face comprising two surfaces offset relative to each other.

.4. A contact member including support means, a strap loosely suspended thereon, a contact finger pivotally suspended on said strap and having a contact-making face the contour of which comprises two sectors ofiiset relative to one another, one of said sectors being curved.

5. A- contact member comprising support means, a pair of oppositely disposed contact elements, each including a strap loosely mounted on said support means and a contact finger pivotally supported on said strap, said contact finger having a contact-making face of such configuration as to provide a hump near the middle thereof and means to bias said contact fingers toward each other.

6. A contact member comprising support means, a'pair of oppositely disposed contact elements, each including a strap loosely supported on said support means and a contact finger pivotally supported on said strap, said contact fingers having contact-making faces the middle portion of the surface of which is further from said pivotal supports than are portions of said surface immediately adjacent each side of said middle portion, and means to bias said contact fingers toward each other.

7. In a cont-act member, the combination including a supporting means, a pair of straps supported thereby, a pair of oppositely disposed contact-supporting members each pivotally suspended on a strap, a contact jaw attached to each of the said contact-supporting members and means for biasing the said contact jaws toward each other.

8. A contact member for the conductors of a circuit interrupter including a pair of supporting members suspended from a conductor, a pair of contact jaws each pivoted to one of said supporting members and means for biasing said jaws toward each other, said jaws being rotated against the bias of the said 10. A contact member for the conductor of a circuit interrupter including a pair of supporting members loosely suspended from said conductor, a contact jaw pivoted on each of said supporting members and means for biasing said jaws and supporting members toward each other, the jaws being separated by their combined movement of rotation and revolution in opposition to the force of said biasing means.

11. A contact member for the conductor of a circuit interrupter including a pair of supporting members, loose engaging means for suspending said supporting members from said conductors, pivot means on each of said supporting members, a contact jaw'supported on each of said pivot means and means for biasing said contact jaws and supporting means toward each other, the jaws being separated by a movement of rotation about said pivot means and a movement of revolution about said loose engaging means.

12. In an electric switch, the combination of a contact structure and a cooperating rela tively movable contact, said contact structure comprising a base portion and two contact fingers carried thereby in opposed relation for engagement with the opposite sides of the cooperating contact, each contact finger comprising a supporting strap loosely suspended from said base portion, a contact member, means for connecting the contact member to the supporting strap, said means permitting limited angular movement of the contact member relative to the supporting strap, a flexible conductor connecting the contact member and the base portion, and a spring biasing the contact member toward the coop erating contact.

13. In an electric switch, the combination of a contact structure and a cooperating rela tively movable contact, said contact structure comprising a base portion having slots therein and two contact fingers carried thereby in opposed relation for engagement with the opposite sides of the cooperating contact, each contact finger comprising a supporting strap which is supported in one of said slots, the thickness of the supporting strap being less than the thickness of the slot to provide for limited angular movement of the supporting strap, a contact member, means for connecting the contact member to the supporting strap, said means permitting limited angular movement of the contact member relative to the supporting strap, a flexible conductor connecting the contact member and the base portion,and a leaf spring fixed to the base por tion and biasing the contact member toward the cooperating contact. I

In testimony whereof, I have hereunto subscribed my name this 31st day of August 1926.

STANLEY T. SCHOFIELD. 

